1. Field of the Invention
The present invention relates to a method of manufacturing a wheel bearing apparatus, and a wheel bearing apparatus.
2. Description of the Related Art
A vehicle, such as an automobile, is provided with a wheel bearing apparatus used to install a wheel so as to rotate with respect to the body of the vehicle. This wheel bearing apparatus includes a hub wheel, an inner ring member, an outer ring, and a plurality of rolling elements (for example, see Japanese Patent Application Publication No. 2005-239115 (JP 2005-239115 A)). The hub wheel has a hub spindle. The inner ring member is fixed to a spindle end portion of the hub spindle. The outer ring is disposed outward of the hub spindle in a radial direction. The rolling elements are provided between an inner ring raceway formed on an outer periphery of the hub spindle and/or the inner ring member, and an outer ring raceway formed on an inner periphery of the outer ring so that the rolling elements can roll.
Each surface of the outer ring and the hub spindle of such a wheel bearing apparatus can be coated with, for example, nickel plating or zinc plating to improve corrosion resistance and quality of appearance. In the hub spindle coated with the plating, the inner ring member is fitted on a small-diameter portion formed in an outer periphery of the hub spindle. The inner ring member is secured to the hub spindle by clinching a spindle end portion of the small-diameter portion outward in the radial direction using a clinching punch.
In a wheel bearing apparatus for a driving wheel, the hub spindle of the hub wheel is formed like a cylindrical shaft, and thus a shaft of a constant-velocity joint is inserted through the hub spindle along a plated inner periphery of the hub spindle. The inner periphery of the hub spindle is provided with a female spline. A male spline formed on an outer periphery of the shaft fits in the female spline, and thus the shaft and the hub spindle are coupled to each other so that power can be transferred in a rotational direction.
Since the plating is applied to the hub spindle of the above-described wheel bearing apparatus and then the spindle end portion is clinched, the plating can be peeled from a contact surface of the hub spindle that a clinching punch contacts. In this case, the peeled plating is caught between the clinching punch and a clinched portion of the hub spindle, producing indentations and scratches on a surface of the clinched portion and reducing quality. Furthermore, scratches are also produced on a surface of the clinching punch, shortening a life of the clinching punch.
The shaft of the constant-velocity joint is spline-fitted in the plated inner periphery of the hub spindle. Thus, the contact of the shaft to the inner periphery of the hub spindle causes peeling of the plating of the inner periphery of the hub spindle. This loosens the fit between the hub spindle and the shaft.